The results from ten years of measuring several parameters of the antarctic atmosphere with tethered balloons

The results from measuring several parameters of the Antarctic atmosphere’s lower layers over the period 2004 through 2014 (Russian Antarctic expeditions 49 through 59) are presented. Such atmospheric parameters as the altitude dependence of the velocity and direction of the ground wind, the level of background radiation, and the concentrations of ozone and singlet oxygen are studied. Devices are installed on board the vessel Akademik Fedorov and at Antarctic ground stations. Tethered balloons are also used.     

Synthesis of neomenthylsulfanylimidazoles

2-Neomenthylsulfanyl-1H-imidazole,1-methyl-2-neomenthylsulfanyl-1H-imidazole, and 2-neomenthylsulfanyl-1H-benzimidazole were synthesized.     

Macromolecular antioxidants based on polysaccharides and 2,6-diisobornyl-4-methylphenol derivatives

New macromolecular antioxidants that were conjugates of dextran or hydroxyethylated starch with functionalized derivatives synthesized from 2,6-diisobornyl-4-methylphenol were prepared. Their antiradical activity compared with derivatives of 2,6-di-tert-butyl-4-methylphenol was studied in a model reaction with 2,2-diphenyl-1-picrylhydrazyl. The studied conjugates exhibited greater activity than sterically hindered phenols not bonded to a polymer chain. The synthesized isobornyl derivatives were more active than previously studied tert-butyl analogs.     

Magnetic and structural properties of Y2Fe15·3Si1·7 alloy under high pressure

Abstract

The pressure dependence of the crystal structure of a powder sample of Y₂Fe_15·3Si_1·7 was studied in the pressure range from 0 to 2 GPa, using the D-2 diffractometer with hydrostatic liquid pressure cell at the IVV-2M reactor (Ekaterinburg) and DN-12 time-of-flight diffractometer with a sapphire anvil cell at the IBR-2 pulsed reactor (Dubna). Also the pressure dependence of the Curie temperature T_c (P) of the alloy was studied. The correlation between the decreases of both T_c and Fe-Fe interatomic distances in “dumbbell” site 4f under pressure was obtained.     

Effect of copper and cobalt impurities on the electronic structure and optical spectra of the intermetallic compound PrNi5

The electronic structure and optical properties of the intermetallic compound PrNi₅ and their evolution during the substitution of copper or cobalt atoms for nickel atoms have been investigated. The band spectra of the studied compounds have been calculated in the local spin density approximation corrected to account for strong electron-electron interactions in the 4f shell of the rare-earth ion (LSDA + U method). The dispersion relations of the optical conductivity in the interband light absorption region have been interpreted using the results of calculations of the electron density of states.     

The Influence of Copper Impurity on the Electronic Structure and Optical Properties of TmNi<Subscript>5</Subscript> Compound

Investigations of the electronic structure and optical properties of TmNi_5–хСu_x (х = 0, 1, 2, 3) compounds were performed. Self-consistent calculations of the band spectrum have been performed in the local electron-spin-density approximation with a correction on strong electron interactions within the LSDA + U method. Total and partial densities of electron states associated with thulium, nickel, and copper atoms have been calculated. Optical conductivity, the behavior of which is interpreted for each compound taking into account the performed calculations, has been measured by the ellipsometry method in a wide wavelength range of 0.22–16 μm. Concentration dependences of plasma and relaxation frequencies of conduction electrons have been determined.     

Optical properties of <Emphasis Type="Italic">R</Emphasis>Ni<Subscript>5</Subscript> intermetallic compounds (<Emphasis Type="Italic">R</Emphasis> = Y,La, Ce)

The paper reports on an ellipsometric study of the optical properties of RNi₅ (R = Y, La, Ce) paramagnetic intermetallic compounds. The dispersion measurements of the refractive index n and of the absorption coefficient k were conducted within a spectral interval 0.083–5.64 eV at room temperature. The behavior of optical interband conductivity with energy is analyzed. The results obtained are discussed in the frame of available information on the electronic band structure of these compounds. The plasma and relaxation frequencies of conduction electrons have been determined.     

Optical properties and electronic structure of YNi<Subscript>5 − <Emphasis Type="Italic">x</Emphasis></Subscript>Cu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> intermetallic compounds

The optical properties of hexagonal intermetallic compounds YNi_{5 − x} Cu _x (x = 0, 1, 2) have been investigated by ellipsometry in the spectral range of 0.22–15 μm. It is shown that the replacement of nickel atoms by copper atoms leads to local changes in the optical-conductivity spectra. A new absorption band is found at 3.5–4.5 eV; its intensity depends on the copper content. The plasma and relaxation frequencies of conduction electrons are determined. The electronic structure and interband optical conductivity of these compounds are calculated within the electron density functional theory using the pseudopotential method. The main parameters of the band structure and the total and partial densities of electronic states are determined. Qualitative agreement is obtained between the experimental and theoretical frequency dependences of the optical conductivity.